Neale, you and I are really on a parallel road with forum members who have an interest in Brills. But, inspired by one of your queries, this will be of interest to all.
I may not have these in order but the captions will sort that out. Only the final image is mine; the rest belong to others:
ricky brill (1).jpg This is an 'early' Brill; it has only one welt in the seam, the cuff is hand stitched on one end and by machine on the other, the stitching on the front side ends with a single stitch at right angles to the main. That main welt line is quite straight, too; on all revolvers and the autos.
ricky brill (3).jpg This is a 'late' Brill; it has two and even three welts in the seam, the cuff is hand stitched at both ends, the stitching on the front side has one more return stitch that parallels the main. The bulge in the welt line is quite pronounced. Made by N.J.
unmarked early brill (1).jpg This unmarked version, is considered the very earliest of the brill-style. Its carving type is very, very similar to the one attributed to Butch Cassidy (d. 1908). The Mexican carving of 'late' Brills by N.J. is very different.
nelson rabensburg (6).jpg This is a known Rabensburg. The image is from Stan Nelson and is one of the two holsters made for him by N.J. in Austin circa 1955. From these two holsters, was derived the 'late' and 'early' formula.
nichols sessums (1).JPG This is a Sessums. The image is mine and is of a holster I bought here in Oz that was discovered in a storage shed that hadn't paid its rent (well, the owner of the goods hadn't). Sessum are also considered collectibles and are less common than Brills. For my money, after I had a 'late' Brill, I'd want a King Ranch version, too.
There were a dozen Texas makers of the Brill style who marked their names on their holsters circa 1910-1920. Rabensburg outlived them all. All were within a 200 mile radius (it's quite exact) of Austin except S.D. Myres; which 'fits' if my Johnny Appleseed theory (Hughes) is correct because Sam Myres did not enter the holster biz until the 1930s.
There are also brill-style holsters that are neither marked, nor obviously constructed by any of the 'name' makers.
It must mean 'something', that I have NO Mexican carved 'early' Brill-marked holsters in my image files, except the one attributed to Cassidy. The carved ones otherwise are always Rabensburgs. Also, there appears to be no such thing, as a plain Brill-marked holster.